.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.TH SCALBLN 3 2021-03-22 "" "Linux Programmer's Manual"
.SH NAME
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
multiply floating-point number by integral power of radix
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double scalbln(double " x ", long " exp );
.BI "float scalblnf(float " x ", long " exp );
.BI "long double scalblnl(long double " x ", long " exp );
.PP
.BI "double scalbn(double " x ", int " exp );
.BI "float scalbnf(float " x ", int " exp );
.BI "long double scalbnl(long double " x ", int " exp );
.fi
.PP
Link with \fI\-lm\fP.
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
.fi
.PP
.BR scalbn (),
.BR scalbnf (),
.BR scalbnl ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.SH DESCRIPTION
These functions multiply their first argument
.I x
by
.B FLT_RADIX
(probably 2)
to the power of
.IR exp ,
that is:
.PP
.nf
    x * FLT_RADIX ** exp
.fi
.PP
The definition of
.B FLT_RADIX
can be obtained by including
.IR <float.h> .
.\" not in /usr/include but in a gcc lib
.SH RETURN VALUE
On success, these functions return
.IR x
*
.B FLT_RADIX
**
.IR exp .
.PP
If
.I x
is a NaN, a NaN is returned.
.PP
If
.I x
is positive infinity (negative infinity),
positive infinity (negative infinity) is returned.
.PP
If
.I x
is +0 (\-0), +0 (\-0) is returned.
.PP
If the result overflows,
a range error occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively, with a sign the same as
.IR x .
.PP
If the result underflows,
a range error occurs,
and the functions return zero, with a sign the same as
.IR x .
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Range error, overflow
.\" .I errno
.\" is set to
.\" .BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.TP
Range error, underflow
.I errno
is set to
.BR ERANGE .
An underflow floating-point exception
.RB ( FE_UNDERFLOW )
is raised.
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR scalbn (),
.BR scalbnf (),
.BR scalbnl (),
.BR scalbln (),
.BR scalblnf (),
.BR scalblnl ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH NOTES
These functions differ from the obsolete functions described in
.BR scalb (3)
in the type of their second argument.
The functions described on this page have a second argument
of an integral type, while those in
.BR scalb (3)
have a second argument of type
.IR double .
.PP
If
.B FLT_RADIX
equals 2 (which is usual), then
.BR scalbn ()
is equivalent to
.BR ldexp (3).
.SH BUGS
Before glibc 2.20,
.\" http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
these functions did not set
.I errno
for range errors.
.SH SEE ALSO
.BR ldexp (3),
.BR scalb (3)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
